This present disclosure relates to an electrode covering material, an electrode structure and a semiconductor device.
Where semiconductor devices are fabricated from conventional silicon semiconductor substrates and the like, a photolithographic technique and many thin film-forming techniques have been in use. However, these fabrication techniques are complicated and take a long time for the fabrication of semiconductor devices, thus presenting a serious obstacle to the reduction in fabrication costs of the semiconductor devices. Existing semiconductor devices are a so-called bulk, thus making it difficult to apply them to fields requiring flexibility and plasticity.
In order to provide an electronic device to be substituted for semiconductor devices based on such conventional silicon semiconductor substrate and the like, e.g. a field effect transistor (FET), intensive studies and developments of devices using conductive polymer materials have been in progress. As a result, a new field of flexible and inexpensive plastic electronics has now been being developed. And a so-called organic field effect transistor whose channel forming region is constituted of an organic semiconductor material layer is well known such as, for example, from Japanese Patent Laid-Open No. Hei 10-270712 and Japanese Patent Laid-Open No. 2000-269515.
In the techniques disclosed in these Japanese Laid-open Patent Applications, the organic semiconductor material layer forming the channel forming region is in direct contact with source/drain electrodes made of a metal. In such a structure as mentioned above, the transfer of electrons at the interface between a metal and the organic semiconductor material layer involves a considerable energy loss. More particularly, the transfer of electrons at the junction interface between the metal and the organic semiconductor material layer is greatly influenced by the metal interface wherein free electrons exist, the interface of the organic semiconductor material layer having a quantized space and the difference in distance and direction therebetween at the junction interface, thus being very inefficient under existing circumstances. As a consequence, problems are involved in the contact resistance being great and the mobility being low.